doc: Clarify refresh options for DROP PUBLICATION

The available refresh options are specified as refresh_options under
REFRESH PUBLICATION, and DROP PUBLICATION itself has an option named
refresh. Clarify what we mean by refresh options to avoid confusion.

Backpatch through v14 where ALTER SUBSCRIPTION ... DROP PUBLICATION
was introduced.

Author: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Reviewed-by: Peter Smith <smithpb2250@gmail.com>
Discussion: https://postgr.es/m/CAD21AoCm1wJ3A8Q9EmBjRbShYkJ+o+Oa_z9O0hvwhvhUa2BSyg@mail.gmail.com
Backpatch-through: 14

doc/src/sgml/ref/alter_subscription.sgml

@@ -126,8 +126,9 @@ ALTER SUBSCRIPTION <replaceable class="parameter">name</replaceable> RENAME TO <
        </varlistentry>
       </variablelist>
 
-      Additionally, refresh options as described
-      under <literal>REFRESH PUBLICATION</literal> may be specified.
+      Additionally, the options described under
+      <literal>REFRESH PUBLICATION</literal> may be specified, to control the
+      implicit refresh operation.
      </para>
     </listitem>
    </varlistentry>